f  UNIV.  OF  FL  LIB. 

nflpAJMENTS  DEPT. 


JEPOSITORY 


A.  I.  26 


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United  States  Department  of  Agriculture, 


JOHN  R.  MOHLER,  Chief  of  Bureau.l»  .  **•  4  •  Co   $ 


WHITE  SNAKEROOT  OR  RICHWEED  (EUPATORIUM  URTI- 
CiEFOLIUJVl)  AS  A  STOCK-POISONING  VlJ&3£;„0tfl$l 

\\\  C.  Dwk.iii  Maksh  and  A.  \\.  Clawson„o/  //k  Pathological  Division. 
THE  CAUSE  OF  MILK  SICKNESS^ 

Among  the  suggested  causes  for  the  disease  popularly  known  as 
milk  sickness,  trembles,  slows,  tires,  elc,  has  been  the  plant -commonly 
called  "  white  snakeroot  " — Eupatorium  urti.cn 'folium,  or  Eupatorium 
ayeratoides  of  the  older  literature.  Many  arguments  have  been 
advanced  both  for  and  against  this  theory.  In  later  years  the  possi- 
bility of  the  connection  of  this  plant  with  the  disease  has  lessened, 
since  Crawford  (1908)  published  his  negative  pharmacological  work, 
and  Jordan  and  Harris  in  1909  published  their  paper  on  the  Bac- 
t<  rium  lactimoihi.  Although  there  have  been  authors  who  clung  to 
the  white  snakeroot  origin  of  the  disease,  it  has  been  believed  rather 
generally  that  the  real  cause  was  not  a  plant  poison  but  more  likely 
a  .disease-producing  germ. 

Somewhat  extended  experiments  upon  this  subject  have  been  car- 
ried on  by  the  United  States  Department  of  Agriculture,  and  though 
the  general  results  of  the  experiments  in  their  relation  to  the  disease 
of  milk  sickness  are  not  in  form  for  publication,  it  has  been  clearly 
demonstrated  that  Eupatorium  urtiaifoVnm  must  be  counted  as 
one  of  the  rather  important  stock-poisoning  plants  which  produce 
serious  losses  of  domestic  animals.  On  this  account,  although  the 
work  is  incomplete,  it  seems  wise  to  publish  a  summary  of  the  results 
so  far  as  they  relate  to  Eupatorium  wrUccefMium  as  a  poisonous 
plant,  with  the  hope  that  some  of  the  losses  may  be  avoided,  for  it  is 
evident  that  while  in  many  localities  this  plant  is  suspected  to  Be  ihe 
cause  of  milk  sickness,  its  importance  as  a  stock-poisoning  plant  baa 
received  little  recognition. 

DESCRIPTION  OF  THE  PLANT. 

Eupatorium  urtim folium  Reiehard  (fig.  1).  quoted  as  E.  agera- 
toides  L.  in  the  older  botanies,  is  a  -lender,  erect,  perennial  herb, 

1  Preliminary  paper. 
18029°— IS 


belonging  to  the  family  Composite.     Its  leaves,  which  are  3  to  5 
inches  long,  are  opposite,  broadly  ovate,  pointed,  sharply  toothed  and 


Fig.  1. — White  snakeroot  or  richweed   (Eupatorium  urticxefolium). 

thin,  and  have  rather  long  petioles.     The  stems  are  viscid- villous. 
The  small  white  flowers  are  in  compound  corymbs  of  8-10  flowers, 


appearing  in  the  late  summer  and  fall.  The  plants  are  from  1  to  4 
feet  in  height. 

It  is  found  widely  distributed  in  the  eastern  United  States  and  as 
far  west  as  Minnesota,  Oklahoma,  Nebraska,  and  Louisiana.  Its 
favorite  habitat  is  in  rich  soil  of  damp  woods.  It  is  abundant  in 
the  groves  along  the  watercourses  of  the  Middle  States  and  grows 
with  especial  profusion  in  the  so-called  coves,  or  damp,  shaded 
ravines,  of  the  northern  slopes  of  the  Southern  Appalachians.  It  is 
by  no  means,  however,  confined  to  shaded  situations,  for  it  sometimes 
grows  in  masses  on  cleared  hillsides  in  the  open. 

It  is  most  commonly  known  as  white  snakeroot.  Other  names 
which  have  been  applied  to  it  are  white  sanicle,  Indian  sanicle, 
deerwort,  boneset,  poolwort,  poolroot,  rich  weed,  squaw  weed,  white 
top,  and  steria. 

The  common  thoroughwort,  Ewpatorium  p'erfollatum  L.,  which 
grows  in  similar  localities,  but  usually  on  soils  with  more  moisture,  is 
readily  distinguished  from  E.  urtiea folium,  as  it  is  a  coarser  plant 
and  the  leaves  are  long,  narrow,  rugrose,  and,  as  the  name  indicates, 
are  without  petioles  and  united  around  the  stem. 

EFFECTS  OF  EUPATORIUM  POISONING. 

The  most  noticeable  symptom  and  perhaps  the  most  typical  is 
trembling,  which  is  seen  especially  in  the  muscles  about  the  nose  and 
in  those  of  the  legs.  This  becomes  marked  after  exercise,  and  may  be 
violent,  ending  in  the  animal  falling  to  the  ground.  In  some  cases 
trembling  is  the  first  symptom  noted,  but  in  others  there  is  a  pre- 
ceding period  of  marked  depression  and  inactivity. 

Most  cases  are  constipated  and  some  have  bloody  feces. 

Generally  when  fed  intensively  the  animals  are  nauseated,  and  this 
is  sometimes  accompanied  with  vomiting. 

The  respiration  is  normal  except  that  it  is  quickened  and  some- 
what labored  during  exertion. 

In  the  average  of  cases  there  are  no  significant  changes  in  tem- 
perature. 

Weakness  is  very  pronounced.  The  animals  have  difficulty  in 
standing,  and  sometimes  remain  down  for  a  prolonged  period  before 
death.  Sometimes  the  animals  live  several  days  after  the  appear- 
ance of  the  first  symptoms. 

It  will  be  noticed  that  these  symptoms  correspond  very  closely  to 
those  popularly  considered  typical  of  milk  sickness. 

The  autopsies  are  characterized  by  a  congested  small  intestine  and 
an  abnormal  condition  of  the  liver. 


ANIMALS   SUSCEPTIBLE  TO   EUPATORIUM   POISONING. 

The  author.-*  experiments  were  with  cattle  and  sheep.  Definite 
feeding  experiments  made  by  others  have  proved  the  toxicity  of 
Eupatorium  for  horses,  and  extracts  from  the  plant  have  poisoned 
cats,  dogs,  and  guinea  pigs.  So  far  as  reported  experimentation  goes, 
it  appears  that  no  animals  are  immune  to  the  toxic  principle  of  the 
plant.  In  regard  to  man  the  definite  evidence  is  hardly  conclusive, 
in  spite  of  a  number  of  instances  in  which  the  plant  or  an  extract  is 
said  to  have  been  poisonous.  Some  of  these  cases  are  clearly  apocry- 
phal. But,  on  the  whole,  there  seems  to  be  little  doubt  that  human 
beings  may  be  poisoned  by  the  plant. 

TOXICITY  OF  THE  PLANT. 

There  is  very  little  difference  between  the  toxic  and  lethal  doses, 
as  determined  by  experiment.  This  does  not  mean  that  no  poisoned 
animals  recover,  but  does  show  the  serious  character  of  cases  of 
poisoning.  Generally  speaking,  the  fatal  dose  for  sheep  is  about  G 
per  cent  of  the  animal's  weight,  and  for  cattle  about  10  per  cent. 
Sheep,  consequently,  are  somewhat  more  susceptible  than  cattle. 

Although  there  is  some  evidence  that  the  toxic  dose  is  smaller 
when  the  material  is  given  in  a  short  time,  this  difference  is  com- 
paratively slight.  It  appears  from  the  experimental  cases  that  the 
elimination  of  the  toxic  substance  takes  place  very  slowly,  so  that 
there  is  a  distinct  cumulative  effect.  This  was  evident  both  in  the 
cattle  and  in  the  sheep. 

The  plant  is  poisonous  when  dried,  but  it  does  not  have  as  much 
effect  as  when  in  a  fresh  state,  so  that  while  Eupatorium  in  hay 
may  be  poisonous  it  is  not  so  dangerous  as  the.  fresh  plant. 

So  far  as  experimental  work  has  gone,  it  seems  quite  clear  that 
the  flesh  of  poisoned  animals  is  not  harmful  to  other  animals  that 
may  eat  it. 

Poisoning  by  Eupatorium  is  produced  by  a  poisonous  principle  in 
the  plant,  and  not  by  disease  germs  carried  by  the  plant  to  the 
animals. 

RELATIONSHIP   BETWEEN  EUPATORIUM   POISONING   AND   MILK 

SICKNESS. 

There  is  no  question  but  that  Eupatorium  urticce folium  is- poisonous 
and  produces  a  line  of  symptoms  closely  resembling  those  said  to  be 
typical  of  milk  sickness  in  cattle  and  other  animals.  Most  cases 
of  the  so-called  milk  sickness  in  cattle  occur  in  localities  where  this 
plant  grows.  Field  eases  seen  by  the  authors  have  the  same  symp- 
toms as  those  which  have  been  observed  in  experimental  animals. 
and  have  been  diagnosed  as  intoxication  by  Eupatorium  urtlccpjoVum . 
There  seems  little  doubt  that  manv  if  not  most  cases  of  milk  sick- 


ness  or  trembles  in  cattle  are  caused  by  this  plant.  It  does  not 
follow,  however,  thai  all  cases  of  milk  sickness  are  produced  by 
Eupatorium. 

Somewhat  extended  bacteriological  investigations  by  the  authors, 
the  results  of  which  will  be  published  in  another  paper,  appear  to 
substantiate  the  claim  of  Jordan  and  Harris  that  there  is  a  bacterium 
widely  disseminated  in  the  soil  and  on  plants,  which,  under  certain 
conditions,  for  the  most  part  unknown,  produces  a  disease  in  man 
and  animals  in  which  symptoms  are  exhibited  which  appear  to  be 
those  of  milk  sickness. 

Very  much  more  work  is  necessary  in  order  to  clear  up  the  subject, 
but  it  seems  highly  probable  at  this  stage  of  the  investigation  that 
under  the  term  "  milk  sickness  "  or  "  trembles  "  are  included  at  least 
two  distinct  things,  one  the  poisoning  of  animals  by  Eupatorium 
urticcefolium  and  the  other  a  bacterial  disease  to  which  both  animals 
and  man  are  susceptible, 

The  question  of  the  difference  between  the  two  diseases  will  be 
discussed  later  in  the  detailed  report  of  the  investigations.  It  may  be 
noted  here,  however,  that  trembling  appears  to  be  more  distinctly 
characteristic  of  Eupatorium  poisoning,  and  that  a  subnormal  tem- 
perature is  one  of  the  distinctive  symptoms  of  the  bacterial  disease, 
whereas  Eupatorium  poisoning  produces  no  distinct  effect  on  the 
temperature. 

CONDITIONS  UNDER  WHICH  ANIMALS  MAY  BE  POISONED. 

It  is  known  that  stock  may  be  pastured  where  E.  urticcefolium 
is  abundant  and  that  the  use  of  these  pastures  may  be  continued  for 
years,  with  no  harm.  Most  of  the  cases  of  poisoning  occur  in  the 
late  summer  and  fall  and  generally  in  years  when  there  is  a  defi- 
ciency of  moisture  and  a  consequent  shortage  of  forage  grasses. 
Cases  also  occur  when  grazing  animals  are  confined  to  a  limited  area 
omwhich  the  plant  is  abundant.  The  experimental  work  shows  that 
E.  urticcefolium  is  not  palatable  to  domestic  animals  and  that  they 
will  avoid  it  in  the  presence  of  other  foods.  As  in  the  case  of  most 
stock-poisoning  plants,  there  is  a  direct  relation  between  shortage 
of  feed  and  cases  of  poisoning,  although,  of  course,  sporadic  cases 
may  occur  under  other  conditions. 

REMEDIES. 

Sick  animals  should  be  treated  with  remedies  to  relieve  the  con- 
stipation and  increase  elimination.  To  this  end  purgatives  may  be 
used,  of  which  perhaps  Epsom  salt  is  the  best;  this  should  be  used 
in  doses  of  1  pound  for  a  1,000-pound  animal.  The  feed  should  be 
laxative,  like  bran,  oil  meal,  etc.     In  parts  of  North  Carolina  it  is 


customary  to  feed  "milk-sick"  animals  with  green  corn  and  pump- 
kin-, and  there  is  good  reason  to  consider  this  a  desirable  diet. 

Inasmuch  as  the  toxic  substance  of  the  plant  is  eliminated  very 
slowly,  quick  recovery  must  not  be  expected,  and  the  animals  should 
be  given  somewhat  prolonged  attention. 

PREVENTION. 

In  many  places  "  milk-sick  "  areas  have  been  fenced  off,  with  con- 
sequent prevention  of  losses.  In  some  localities  where  Eupatorbna 
urticcefoUum  is  particularly  abundant  this  evidently  is  advisable. 
Clearing  of  land  and  seeding  to  corn,  grain,  or  grasses  will  of  course 
stop  the  trouble.  It  has  long  been  known  that  "  trembles  "  affects 
animals  pastured  on  unbroken  land  and  that  the  disease  disappears 
after  cultivation. 

So  far  as  getting  rid  of  the  plant  is  concerned,  however,  it  must 
be  remembered  that  partial  clearing  is  not  sufficient.  It  is  true  that 
the  plant  favors  damp  and  shaded  places,  but  it  sometimes  grows 
most  luxuriantly  on  partially  cleared  land.  It  has  been  noticed  in 
the  mountains  of  North  Carolina  that  the  plant  increases  enormously 
in  cleared  land  and  only  disappears  after  the  land  has  been  seeded 
down.  When  the  poisonous  character  of  the  plant  is  recognized 
much  can  be  accomplished  by  so  handling  the  animals  that  they  do 
not  graze  largely  in  areas  where  it  is  particularly  abundant. 

In  this  connection  it  may  be  noted  that  inasmuch  as  it  takes  a 
fairly  large  quantity  to  poison  an  animal,  little  harm  will  result  from 
eating  the  plant  for  a  short  time  unless  the  animal  is  unusually 
hungry.  Poisoning  is  more  likely  to  follow  from  continued  feeding 
as  a  result  of  which  the  toxic  substance  has  a  chance  to  accumulate 
in  the  system. 

SUMMARY. 

1.  Eupatorium  urticcefoUum  has  for  some  years  been  considered 
by  many  people  the  cause  of  milk  sickness  in  cattle. 

2.  Experimental  work  shows  conclusively  that  the  plant  is  toxic 
and  produces  a  definite  line  of  s}Tmptoms  bearing  a  close  resemblance 
to  those  considered  characteristic  of  trembles. 

3.  Probably  •many,  possibly  most,  cases  of  trembles  in  cattle  and 
sheep  are  due  to  poisoning  by  E.  urthw folium. 

4.  Under  the  term  "milk  sickness"  or  "trembles"  are  probably 
grouped  at  least  two  distinct  things — (1)  poisoning  by  E.  urticce- 
folium,  and  (2)  a  bacterial  disease. 

5.  Losses  of  live  stock  should  be  avoided  by  prevention  rather  than 
by  reliance  upon  remedies. 


PUBLICATIONS    OF    THE   U.    S.    DEPARTMENT    OF    AGRICULTURE 
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AVAILABLE   FOR   FREE   DISTRIBUTION. 

Larkspur,  or  Poison  Wood.     (Farmers'  Bulletin  531.) 

Weeds:  How  to  Control  Them.     (Farmers'  Bulletin  660.) 

Drug  Plants  Tudor  Cultivation.     (Farmers'  Bulletin  663.) 

Prevention  of  Losses  of  stock  from  Poisonous  Plants.    (Farmers'  Bulletin  720.) 

Ginseng  Diseases  and  Their  Control.     (Farmers'  Bulletin  736.) 

Cicuta,  or  Water  Hemlock.     (Department  Bulletin  G91.) 

Zygadonus,  or  Death  Camas.     (Department  Bulletin  125.) 

Lupines  as  Poisonous  Plants.      (Department  Bulletin  40o. ) 

Principal    Poisonous   Plants  of  the  Western   Stock   Ranges.      (Bureau   of   Plant 

Industry  Miscellaneous.) 
Menzusia,  a  new  Stock-Poisoning  Plant  of  the  Northwestern  States.     (Bureau 

of  Plant  Industry  Miscellaneous.) 

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